Tractor-trailers are the preferred mode of transportation for commerce today and will remain to be in the years to come. The tractor-trailer combination provides a cost-effective mode of shipping a wide variety of goods within provincial/state boundaries-and also across the country.
The widespread use of tractor-trailers by the trucking industry and the increased congestion on the major thoroughfares and highways has given rise to safety concerns. In particular, the loss of a wheel from a truck or tractor-trailer, even at low speeds, can cause significant damage if it collides with another moving vehicle or crashes into a building alongside the roadway. In recent years, the problem of "wheels flying off" has come to the forefront in light of an increasing number of highly publicized fatalities resulting from collisions between a wheel assembly lost from a tractor-trailer and another vehicle.
In some cases, a truck will lose a wheel as a result of catastrophic mechanical failure, for example, an axle in the trailer breaks. In other cases, poor installation or servicing results in the bolts holding the wheel to the axle being sheared off or vibrating loose over the course of a long-haul journey. In both cases, the disconnected wheel becomes a heavy flying projectile moving at speeds upwards of 60 mph (100 kph). Collision between the flying wheel and another vehicle usually results in significant injury or fatality.
In Ontario, the problem of flying-off wheels has prompted the Provincial Legislature to enact laws to force truck operators to strictly maintain their rigs to prevent injury or fatality as a result of mechanical failures which may lead to a wheel flying off the vehicle.
Accordingly, there is a need for a safety device which will detect the loss of a wheel from a vehicle and prevent the wheel from escaping completely from the vehicle.